Colorado’s proposed rule requiring drillers to disclose the ingredients in their fracking fluids drew fire from both environmentalists and industry representatives at a hearing Monday.

While both sides supported the basics in proposal from the state Oil and Gas Conservation Commission, each sought changes to the rule.

The commission is slated to make its final decision on the rule Monday at its monthly hearing in Greeley. The proposed rule requires drillers to file fracking fluid ingredients on FracFocus.org — a public-access Internet database.

Fracking fluids are pumped into wells under pressure to fracture rock and release more oil and gas. Water and sand make up about 99 percent of the fluid, but the other 1 percent is composed of as many as 40 other chemicals to make the fracturing more effective.

Changes that environmental groups, such as the Colorado Environmental Coalition and the High County Citizens Alliance, want include:

• Tightening of the trade-secret provision, which allows a company to not disclose a chemical by declaring it proprietary.

About 6 percent of the chemicals used in Colorado wells this year were identified as propriety, according to an oil and gas commission review.

• A shortening in the reporting deadline for filing disclosure from the 60 days in the proposal to 30 days, as required in Montana, Idaho and Wyoming.

“Disclosure isn’t for the industry, they know what they are using,” Gwen Lachelt, head of the Earthworks Oil and Gas Accountability Project, told the commission. “Disclosure is for the public.”

Testimony by oil and gas industry representatives identified several areas in the rule that they thought should be changed, including:

• Dropping a requirement that the data can be searched by chemical. The industry says the rule is unnecessary.

• Changing a requirement that all chemicals and their concentrations — including ones that do not have detailed safety information — be disclosed. An industry proposal would disclose the chemicals in that group, but not the concentrations to protect individual industry products.

Mike Watts, an executive with the oil service company Halliburton, said the proposed rule would reveal enough information to allow competitors to figure out their products.

The chemicals that are added to the fracking fluid are there to improve the efficiency of the process and get larger volumes of oil and gas out of the well.

But Mike Freeman, an attorney with the environmental law group Earthjustice, counted: “You can’t assess the risk without knowing the concentration.”

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